1. Field of the Invention
The present invention relates to sheet materials including surface fasteners. In particular, the present invention relates to sheet materials having surface fastening elements which may be used in the field of closures and more particularly in the field of flexible bag closures.
2. Description of Related Art
Sheet materials are used in many industries for the production of a large number of products which ultimately serve a variety of purposes. Some of these uses include the manufacture of webs in the form of one layer articles as well as multilayer laminates which function in the manufacture of containers and receptacles. Containers and receptacles ultimately serve the function of holding a product and therefore require closures for the protection of the container""s contents.
Closures currently know in the art may be broadly divided into three categories: a) adhesive attachment closures; b) rail fasteners; and c) hook and loop closures. Adhesive attachment closures are characterized by the use of materials which have different levels of adhesiveness or xe2x80x9ctackiness.xe2x80x9d A large number of adhesives are used in the closure industry to either permanently seal a product, such as a bag, and render the seal inoperable after initial opening or to non-permanently seal a product and allow for repeated opening and closure of a product. The adhesiveness of the material used depends on the particular application and will vary according the peel and sheer strength necessary.
The permanent seal product is commonly known in the industry as a xe2x80x9cpeel-sealxe2x80x9d and after initial adhesion, the product may be opened through pull-apart force. Once this xe2x80x9cpeel-sealxe2x80x9d has been opened, or separated, the properties of the adhesive no longer maintain their adhesiveness or tackiness, thereby preventing resealing of the product. Such a seal is primarily useful with products which will be quickly utilized or consumed, such as snack foods or other edibles which are packaged in small containers. A second benefit of such a seal is that it is tamper-evident and allows a user, which encounters the product, to determine if the closure has been opened. The major drawback to such a closure system is its lack of resealing properties. If a user does not utilize or consume the package contents, a secondary form of closure is necessary. Snack chip bags, such as those used for tortilla or potato chips, are exemplary of this closure system. An entire industry has developed around the need for a secondary closure for such closure systems in the form of xe2x80x9cchip-clipsxe2x80x9d which provide a reusable closure after the peel-seal has been opened.
Non-permanent seal products are also known in the industry and maintain their adhesiveness, or tackiness, after initial opening. These utilize a different type of adhesive that will maintain its adhesiveness after the initial opening of the product. The major convenience offered by such a closure system is based on the ability of a user to initially open a container or receptacle, such as a bag, remove contents, and reseal the container or receptacle. This allows the contents to remain fresh and helping to prevent the intrusion of unwanted objects, such as dust, and organisms, such as insects, into the container. U.S. Pat. No. 4,786,190 (""190), entitled xe2x80x9cReclosable Package Having Outer Reclosable Closure and Inner Non-Reclosable Closure,xe2x80x9d discloses a bag having wall panes which define a receptacle space. This reference is of interest for showing a bag having a closure system which includes a one-time openable non-reclosable peel seal closure in combination with a reclosable closure system which may be a pressure sensitive adhesive. Although the ""190 patent discloses the combination of a peel-seal along with a reclosable closure system, it suffers from its inapplicability to receptacle contents which are in particulate form. If such a package were utilized with products such as snack foods, the pressure sensitive adhesive would immediately adhere portions of the snack food and loose its adhesive abilities. After only a few uses the reclosable portion of the package would be inoperable for its intended purpose and a secondary form of closure would be necessary.
A further disadvantage of the adhesive closure is the adhesive itself. In the comestible food industry, be it for human or animal consumption, the contact between chemical adhesives and food items is not advisable. A further difficulty is presented when the food is intended for animal consumption. Most animals, and especially dogs, have a heightened sense of smell. If a closure system is necessary for a container which will hold dog food, for example, the adhesive closure system will pose a problem due to the aromatic byproducts of the adhesives. Dogs and other animals will avoid food which has been exposed to adhesives or packaged in containers which utilize adhesives. Therefore, adhesive closure systems are only useful under limited circumstances.
Rail fasteners are also well know in the art and are commonly used for closures, particularly bag closures. These assume the configuration of a groove, commonly constructed from plastic, and a corresponding, complementary tongue that fits into the groove to create a closure system. The rail fastener systems, when used for bag closures, provide users with the benefit of a reclosable closure system which does not adhere to the container contents and still allows for repeated use as the contents of the container are used. One drawback to the traditional rail fastener closure system is that it is difficult to utilize. If the tongue and groove are not accurately positioned, the user might attempt, repeatedly, to make the necessary tongue and groove seal without success.
Of even greater concern is when such a seal is utilized in comestible items such as snack foods and pet foods. If the user does not make a proper tongue and groove seal or a partial seal, it might appear that a seal has been made, when only a partial seal has taken place. Such a partial seal allows dust and organisms, such as bacteria or insects, to intrude into the package container, ruining the package contents and possibly jeopardizing the health of the consumer, be it a human or an animal. An alternative form of rail fastener is illustrated in U.S. Pat. No. 4,706,297 (""297), entitled xe2x80x9cFoldable Top Bag and Method.xe2x80x9d The ""297 patent discloses a collapsible bag with complementary reclosable fastener structures carried on the outer faces of the upper wall portions. The fasteners may be in the form of complementary, extruded, multi-profile fastener strips having a plurality of resiliently flexible, arrow-shaped profiles. The fasteners strips may also be in the form of a plurality of spaced, parallel, extruded plastic, multi-profile fastener strips. Both of these rail fasteners attempt to solve the problem of accurately matching of the tongue and groove to create a closure by providing either a plurality of resilient flexible, arrow-shaped profiles or a plurality of spaced, parallel, multi-profile fastener strips.
A further form of closure system is the hook and loop fastener. This type of closure typically assumes the configuration of woven or extruded hooks and loops. The loop portion of the fastener system relies on a multiplicity of raised loops which allow for the hook portion of the fastener system to engage. The hook is commonly constructed in a similar manner to the loop portion but usually of a stronger or higher denier thread. If the hook is woven, the loops created after the initial weaving function must be cut, or sheared, to create a severed product. This severed loop is thus transformed into a hook and engages the complementary raised portions of loop to create a hook and loop closure system. If the hook is extruded, it will assume the required shape of a hook upon hardening and similarly engage the raised portion of loop.
Such hook and loop closures provide a great advantage to the reclosable container industry but also lacks the ability to provide a tamper-evident initial closure. If a hook and loop closure system is utilized for comestibles, there is still a need for an initial, tamper-proof closure prior to the initial opening of the product. An even greater difficulty presented by the use of hook and loop closures is the need to adhere the hook and loop elements to the walls of the appropriate sheet material. If the hook and loop closure system is being utilized on a bag closure, it will be necessary to adhere the product to the wall portions of the bag. Such adherence is currently performed through adhesive attachment, thread attachment through a sewing process, or by heat welding the product to the wall portions of the bag.
If the bag is intended to hold comestible items, it is quite common to construct the wall portions with a polyester material, due to the strength and puncture resistance provided. The drawback to the use of polyester in conjunction with a hook and loop closure is that heat welding is not possible with a polyester surface. Because the melting point of polyester is so high, heat welding is not an option, thereby reducing the attachment of the hook and loop elements to a sewing process or adherence with an adhesive element.
It is therefore an object of the preset invention to remedy the inadequacies of the prior art with a sheet material including a surface fastener which may be used in closure systems such as bag closures.
It is a further object of the present invention to provide a sheet material including a surface fastener which allows for the use of complementary hook and loop elements but does not required adhesive bonding.
It is still another object of the present invention to provide a closure system which may be utilized for the closure of containers, such as bags, and which allows for an initial tamper-evident closure along with a secondary, complementary hook and loop closure.
The foregoing objects and advantages of the invention are illustrative of those that can be achieved by the present invention and are not intended to be exhaustive or limiting of the possible advantages which can be realized. Thus, these and other objects and advantages of the invention will be apparent from the description herein or can be learned from practicing the invention, both as embodied herein or as modified in view of any variation which may be apparent to those skilled in the art. Accordingly, the present invention resides in the novel methods, arrangements, combinations and improvements herein shown and described.
In accordance with these and other objects of the invention, a brief summary of the present invention is presented. Some simplifications and omission may be made in the following summary, which is intended to highlight and introduce some aspects of the present invention, but not to limit its scope. Detailed descriptions of a preferred exemplary embodiment adequate to allow those of ordinary skill in the art to make and use the invention concepts will follow in later sections.
According to a broad aspect of the invention, a sheet material including a surface fastener is disclosed. The sheet material consists of at least one face which defines at least one opening. A surface fastener having at least one fastening surface which is smaller than the surface fastener. The opening, or openings, are adapted to receive the surface fastener. The surface fastener is bonded to at least one face of the sheet material such that the fastening surface may fasten to another complementary fastening surface.